The objective of the electron paramagnetic resonance core (EPR Core) in this research program is to provide the technical support and consultative expertise to insure success for those aspects of the research projects that require EPR spectroscopy. In addition, it is a goal of the EPR Center to develop new methods and tools that will permit the project leaders to pursue research directions that currently are not possible. The EPR Core will provide facilities and expertise to pursue experiments in the following general areas: 1. detection of free radicals generated by the systems being studied in the various projects, direct EPR detection when possible or detection using the EPR spin trapping technique; 2. the detection of nitric oxide; 3. the role of iron catalysts in free radical processes; 4. analysis of alterations in membrane biophysical properties employing EPR spin probes and fluorescent polarization techniques; and 5. development and understanding of the EPR spin trapping of lipid- derived radicals from cells.